In 2005, Woolf was in labor with her first baby, a boy, at a large Los Angeles hospital. She had pushed for no more than two minutes when her doctor announced he was going to perform an episiotomy -- using sterile scissors to snip an incision and expand her vaginal opening.

Woolf hadn't had much in the way of a birth plan. But in her prenatal visits, she had been explicit about not wanting an episiotomy.

Her doctor said, "Oh yeah, it shouldn't be a problem. Sounds good," Woolf recalled. "But when we got into the delivery room, it was, 'I've got to do this, I've got no choice. If I don’t cut you, you're going to tear. It's going to be terrible. it's going to be way worse.'"

She was 23, in pain despite getting an epidural painkiller and had never given birth before.

"It's a super-vulnerable time, that moment when you're about to push a baby out," said Woolf, who now has three more children, including 11-month-old twins. "You'll basically do anything."

Few women go into the delivery room planning to have an episiotomy -- a cut made in the delicate tissues between a woman's vagina and anus. But many do, and episiotomy has become a common, if under-discussed, aspect of hundreds of thousands of women's birth stories in the last century.

Though there is not one central source for comprehensive, current statistics on episiotomy rates in the U.S., a handful of health organizations do track the procedure.

According to the 2009 National Hospital Discharge Survey, 307,000 episiotomies were done in the U.S. that year. The American Congress of Obstetricians and Gynecologists found that in 2007, the most recent data it has, 443,000 episiotomies were performed. A 2005 study in the Journal of the American Medical Association suggested that between 30 to 35 percent of vaginal births in the U.S. involve an episiotomy. In Europe, rates range from 10 percent of all vaginal deliveries in Denmark to 80 percent in Portugal. Among midwives, who generally perform fewer interventions, episiotomy rates in the U.S. are at or below 3 percent.

Despite these varying estimates, experts agree that there has been a drop in episiotomies since the procedure became a routine part of hospital births, starting in the 1920s.

By the 1930s, most obstetric textbooks endorsed the procedure, arguing that proactive cutting may prevent extensive tearing, which can occur as the vagina stretches during birth. Natural tears occur in 40 percent to 85 percent of all women who deliver vaginally, according to the Journal of Midwifery and Women’s Health.

Vaginal tears are classified by four degrees. Third- and fourth-degree tears are the deepest and are usually repaired in the operating room, whereas first- and second-degree tears are typically stitched in the delivery room, with a shot of local anesthesia.

"People were taught in the '50s and '60s that routine episiotomy was good for the woman," said Dr. Robert Barbieri, chair of obstetrics and gynecology and reproductive biology at Brigham and Women's Hospital in Boston. "What they thought is that if they did a routine episiotomy, they'd have a chance to repair it and that during the repair, they could actually create a better perineum than if they hadn't done it. The idea [was] that we could 'tighten things up.'"

By the 1980s, episiotomies were being performed in more than 60 percent of vaginal births in the U.S., which is when researchers started to take a harder look at the practice as part of a broader shift toward ensuring decisions about patient care were backed by scientific research.

Clinical trials conducted in the '80s and '90s found that episiotomy cuts can, in fact, turn into even deeper lacerations during delivery, damaging the area around the rectum. Then, in 2005, a sweeping review published in the Journal of the American Medical Association found no benefits to routine episiotomy. A year later, the American Congress of Obstetricians and Gynecologists issued new guidelines, saying that episiotomy during labor should be restricted because doctors had previously underestimated the risk of bad outcomes later on, such as painful sex and possible incontinence.

"Now, [medical] residents know we don't do episiotomies unless, in our clinical judgment, we feel it is indicated," said Dr. John Repke, an OB-GYN with Penn State's College of Medicine, who helped draft the guidelines. An example: Doctors might decide to perform an episiotomy if the fetal heart rate is dropping and they need to get a baby out fast, he explained.

That was the case with Lisa, a 37-year-old stay-at-home mom from Philadelphia who had an episiotomy when she gave birth to her first child, a son, in 2006. Lisa, who asked that only her first name be used, had been pushing for four hours and was exhausted when her doctor decided to make the cut. She doesn't recall her doctor saying anything to her about the episiotomy as he performed it, but she had made it clear ahead of time that she did not want all the details about what was going on.

"His heart rate had gone down," Lisa said. "So they had to use a vacuum, and they just kind of ripped him out." (Often, episiotomies are performed in so-called "operative" deliveries, when practitioners use a vacuum or forceps to remove the baby.)

According to the National Institutes of Health's Medline Plus, doctors might also decide to do an episiotomy if a baby's head or shoulders are too big to fit through the vaginal opening, or if the baby is breech, delivered feet-first.

Barbieri, of Brigham and Women's Hospital, said there are geographical "pockets of continued use of routine episiotomy" in the U.S., which a 2005 Agency for Healthcare Research and Quality report attributed to different professional norms, training and doctors' preferences.

Some women, like Woolf, said they are convinced that hospital practices and personal proclivities can create "episiotomy-happy" doctors who do the procedure even when there are no strong medical grounds.

When Woolf delivered her second child, a daughter, she chose an OB-GYN who made it clear that he did not perform episiotomies unless absolutely necessary. That time, there was no ripping and no cutting. Though second-time moms are not as likely to tear, Woolf said she thinks her less dramatic second birth had more to do with her OB-GYN’s philosophy than her own body's changes.

During labor, Woolf's doctor massaged her perineum, which, according to some research, relaxes the area, allowing it to widen. Woolf pushed maybe two times, she recalled, and then her daughter slid out. She called the whole experience "perfectly perfect" and said her recovery was quick: A day later, she took her new baby on a two-mile walk.

Recovering from her episiotomy three years earlier, by contrast, was protracted and painful. It was weeks before Woolf could walk comfortably, and she sobbed when she ran out of the cooling pain-relief spray she'd been given at the hospital.

Even after the worst passed, it took a full year for Woolf to feel right.

"The scar tissue was very itchy," she said. "I felt like I had a yeast infection for a year."

Lisa said the most difficult part of getting an episiotomy was the recovery period. She needed 60 stitches for her third-degree laceration. Her epidural had worn off, and though her doctor later assured her he had given her a local anesthetic, she said she "really felt everything" as he sewed her up.

"It was horrendous," Lisa said.

Nonetheless, she said she has no anger about the episiotomy, or the one she had later with her second son. She said she believes her doctor did the best he could.

"It wasn't like, 'I'm not going to have another kid because of this episiotomy thing,'" said Nicole, 35, a mother of two from Maryland who had an episiotomy with her first baby in 2005 and who also asked that only her first name be used. In fact, her husband was almost more traumatized than she was.

Perhaps that is why for all the attention now being paid to different birthing philosophies and outcomes, to medicated versus unmedicated births, and hospital versus home, episiotomies have remained something of an afterthought in the conversation.

"Caesarean is so dramatic," Barbieri said. "Episiotomy will sometimes be described as 'I'm just going to make a little snip.'"

But for some women, it is a little snip that shapes how they experience and remember giving birth, and that can have lasting physical and psychic consequences.

"I had a shitty experience that led to a really incredible one," Woolf said. "For me, it's just important to share [my story] with other people, so that other women will put up a little more of a fight than I did."